In the deep sub-micron era, global planarization has become an essential process for high density IC processing. Slurries were adopted as abrasive in chemical mechanical polishing processes for producing global planarization of a wafer surface. Slurry blending requirements vary from process to process, i.e., slurry must be blended to meet a tools-specified blend ration. Tungsten and copper slurry were blended from slurry concentrate with DI water and oxidizer. The accuracy of oxidizer concentration present in the slurry significantly influences the polishing ration. Therefore, an efficient and reliable sampling and titrating device is strongly required for slurry blending system. For cost reduction, usually, one titrating device must measure slurry samples from a low pressure mixing station and a high pressure dispensing module respectively. Therefore, a sampling six-ports valve used in a titrating device can be very easily damaged by high pressure slurry dispensed from a high pressure dispensing module. When the sampling six-ports valve is damaged, it causes the titration device to take more samples than desired and causes a wrong reading of the slurry measurement.
It is an object of the present invention to provide a pressure reducer to keep the sample flow through a six-port titrating device stable, thereby increasing the measuring accuracy and lifetime of the sampling valve.
It is an object of the present invention to provide a pressure reducer that automatically decreases flow pressure from a high pressure incoming slurry sample without adding any extra media or slurry.
It is an object of the present invention to avoid slurry crystallization by providing a pressure reducer free of dead space.
It is another object of the present invention to provide a pressure reducer in a sampling device that can reduce loop pressure within a titration device and keep the sample flow stable.
It is another object of the present invention to increase the measuring sensitivity by taking accurate quantity of samples for a titrating device.
It is another object of the present invention to provide a device to allow a constant flow and low pressure for a titrating system to increase the lifetime of sampling valves.
It is another object of the present invention to provide a pressure reducer that does not have a metal spring to decrease the risk of metal contamination within a titrating system.
It is another object of the present invention to provide a pressure reducer for hazardous chemical such as slurry using in a CMP process for flow of slurry through a titrating system.